This invention relates to a hitch for attaching a trailer to a towing vehicle and more specifically, to an improved trailer hitch which allows for automatic aligning and coupling of the trailer to the towing vehicle.
Trailer hitches which permit alignment of the trailer with the towing vehicle comprise generally a movable coupler having a rearward portion loosely connected to the forward end of the trailer and a forward portion having a socket for engagement with a ball on the towing vehicle. The forward end of the trailer has spaced-apart vertically-oriented guide plates which converge rearwardly toward a slot. The rearward portion of the coupler has an arm with a wheel rotatable about a vertical axis mounted to its end. As the forward portion of the movable coupler, which is attached to the towing vehicle, is moved in a horizontal plane through an angle by the rearward movement of the towing vehicle, the wheel connected to the rearward portion of the coupler contacts respective guide plates and rides along the rearwardly converging guide plates until the wheel is seated within the slot in the trailer, thereby providing alignment of the trailer with the towing vehicle. The movable coupler is then securely connected to the trailer by a manually-operated locking device.
Trailer hitches of the above-described configuration possess inherent disadvantages. They are generally incapable of vertical movement which is necessary to facilitate connection of the socket on the coupler with the ball on the towing vehicle. Accordingly, one must use the jack on the forward end of the trailer to raise the trailer and permit the socket of the coupler to be attached to the ball on the towing vehicle. Additionally, because the wheel seated within the slot provides a single point of connection of the coupler to the trailer, lateral stresses are concentrated at this single point connection during turns and other maneuvers. Also, because the arm with the attached wheel does not conform to the shape of the rearwardly converging guide plates, extreme angular deviations of the forward end of the coupler are possible when the towing vehicle is backed up in the process of coupling, even to the extent where the arm may approach a guide plate at a right angle, thus requiring a large force to align the trailer with the towing vehicle.
U.S. Pat. Nos. 3,612,576 and 2,973,971 are directed to the above-described trailer hitches.